Step 7: Wiring the Blimp
I originally used a lot of heavy wiring and connectors in the name of neatness and convenience, but gave it up after I saw how much weight I had added. The result is a slightly tangled but very functional layout.
You should start by building your h-bridges -- if you haven't already, look at Mark Tilden's website for an excellent diagram. You'll probably want to build them on little boards so you can test them with your motors individually before soldering them in.
Once you've got those, you should start thinking about powering your circuits. I cut off the connector the battery came with -- you should too, it saves you 10 grams -- and replaced it with light wires ending in 0.1" sockets, so it can still be easily removed for charging. It plugs into pin headers that I soldered onto the through-hole board. I also put the 7805 on the board, so the power wires for the servo, radio, and Arduino originate from there. The two NPN transistors that the motors draw from (and that the Arduino PWM's ) are also in the board, with the "collector" pin connected directly to the 7.4V of the battery. Again, see the diagram.
Using the socket wires, I connected the Arduino to the h-bridges, radio, servo, and motor transistor. That green chip turned on its side is the TX module. The location for the h-bridges is pretty obvious -- one on either side of the servo. If you get the orientation of the motors wrong (for example, you push forward and it goes back), remember that it's really easy to change by swapping direction pins on the Arduino, or just by changing a line of code.